Renewable energies
Custom dimensions, limited access, and years between maintenance windows — you need the right seal the first time.
Hydropower infrastructure operates under conditions that make standard catalog sealing impractical. Turbine shaft diameters measured in meters, gate seals that must function after years of continuous submersion, and hydraulic systems cycling at pressures that destroy off-the-shelf cylinder seals. Most hydropower sealing is custom — profiled extrusions, molded units, field-spliced cord rings, and large-bore hydraulic components sourced to plant-specific dimensions. Getting the material and geometry right the first time matters: the next maintenance window may be years away.
Our Products
ELASFOR Product Line — Hydropower Applications
| ELASFOR Product | Hydropower Application |
|---|---|
| Field-spliced large-diameter static seals on spiral casing access covers, penstock manholes, and turbine inspection ports — any diameter, vulcanized or cyanoacrylate splice | |
70×70
|
Gate seals, stop log seals, bulkhead seals, trash rack seals — P-seal, J-seal, T-seal, double-bulb, and omega profiles in EPDM, Neoprene, or Natural Rubber |
70×70
|
Kaplan blade trunnion seals (profiled polyurethane lip units), turbine shaft seal rings, large-diameter formed units, factory-vulcanized gate seal corner pieces |
70×70
|
Governor servomotor cylinders, wicket gate actuators, pitch control cylinders — polyurethane U-cups, rod seals, piston seals, wiper seals, buffer seals; rated to 300+ bar |
70×70
|
Wicket gate stem packing (PTFE rope), spring-energized backup rings on large-bore static seals, turbine shaft segmented backup rings |
70×70
|
Wicket gate stem gland packing (PTFE, graphite, carbon fibre impregnated); turbine shaft gland packing on legacy units; pump gland packing in auxiliary systems |
70×70
|
Penstock flanged spool joints, spiral casing manhole covers, instrumentation flanges — EPDM, Neoprene, graphite; custom-cut to any diameter |
70×70
|
Governor OPS valve bodies, instrumentation pressure taps, cooling water circuit connections, hydraulic manifold ports — NBR for turbine oil; EPDM for water circuits |
| High-pressure penstock instrument flanges, governor OPS accumulator ports, fire-resistant fluid system connections — spiral wound with graphite or PTFE filler |
Most hydropower seals are non-standard dimensions. We source custom extrusions, cord-spliced rings, and molded units to your drawings or field measurements — including factory-vulcanized gate seal corner pieces.
Applications
Common Sealing Applications
Turbine Main Shaft Seals
Francis and Kaplan turbine shafts ranging from 500 mm to over 4,000 mm diameter. Complete sealing is intentionally not achieved — controlled leakage of 10–90 L/min flushes frictional heat from the seal faces. Radial carbon ring seals handle heads below 70 m; axial face seals are required above 0.7 MPa or for shafts exceeding 1,000 mm diameter.
Peroxide-crosslinked EPDM for elastomeric components in continuous water contact — sulfur-cured EPDM ages poorly under sustained immersion. Elastic polymer (Thordon SXL type) or PTFE composite ring material for abrasive/silty water where carbon ring brittleness is a failure risk. Barrier water filtration to 25 microns max.
IEC 60308:2024 · ISO 10816 (vibration limits) · Shaft sleeve finish: Ra 0.4–0.8 µm
Wicket Gate & Guide Vane Stem Seals
Upper and lower stem glands on wicket gates (guide vanes) controlling flow through the turbine. Stems operate in slow oscillating rotation under full turbine head pressure. Gland packing remains common on older units; modern designs use V-ring stacks or U-cups with composite bushings. Stem corrosion from packing leakage is the primary driver of gate seizing.
Cut packing rings at 45° ship-lap on a mandrel matching stem diameter; stagger joints 90° apart in the stuffing box. PTFE rope packing for chemical inertness in silt-laden water. HNBR U-cups where water temperature exceeds 50°C in tropical or geothermal-adjacent plants. Replace bronze bushings at ≥ 10-year intervals regardless of apparent condition.
IEC 60193 (gate leakage limits) · Gland follower engagement: min 3 mm inside stuffing box
Governor Hydraulic Systems & Servomotor Cylinders
Oil pressure systems (OPS) operating at 6–16 bar typical, up to 100+ bar on compact governors. Servomotor bore diameters of 150–600 mm. Fluid is mineral turbine oil ISO VG 46/68 on most installations; fire-resistant phosphate ester where regulations require. Polyurethane seals are the material of choice — pressure capability to 500 bar and abrasion resistance far beyond NBR in this cyclic service.
Polyurethane (Shore 90–95A) for rod and piston seals in mineral oil service — 5× the abrasion resistance of NBR, 25-year shelf life. Do not use polyurethane with phosphate ester fluid — FKM or PTFE required. NBR adequate for low-pressure auxiliary circuits. HNBR where oil temperature exceeds 100°C continuously.
IEC 60308:2024 (OPS acceptance) · ISO 4413 · ISO 6020/6022 · ASTM D2000
Gate Seals, Stop Logs & Bulkhead Seals
Vertical lift gates, radial (Tainter) gates, stop logs, bulkheads, and sluice gates. Profiles are extruded to custom cross-section in continuous lengths and cut/vulcanized to fit gate perimeters that can exceed 20 meters. Profile selection (P-seal, J-seal, T-seal, double-bulb) depends on gate geometry, head pressure, and whether sealing is uni- or bidirectional. PTFE-clad faces reduce sliding friction on vertical lift gates by over 70%.
EPDM (peroxide-crosslinked) preferred for permanent water immersion — maintains flexibility to −40°C, critical for Quebec and northern operations where NR becomes brittle. Neoprene where oil-contaminated water is possible. Factory-vulcanized 90° corner pieces mandatory — field-glued corners fail. Hollow bulb for flexible gate frames; solid bulb for stop logs and bulkheads under sustained high head.
ASTM D2000 · DIN 7865 · EM 1110-2-2104 (USACE) · EPDM spec: min 20.7 MPa tensile, 450% elongation, −40°C brittleness
Kaplan Runner Hub & Blade Trunnion Seals
Kaplan and bulb turbines with 4–8 adjustable blades; trunnion diameters 600–1,000 mm; hub oil volume approximately 3,000 L at pressure slightly above river head. The seal simultaneously excludes river water from the hub and retains pressurized turbine oil from reaching the waterway — any detectable oil sheen triggers mandatory environmental reporting in most jurisdictions. Split-design profiled polyurethane lip seals install without blade removal and self-compensate for variable cross-section from droop.
High-performance thermoset polyurethane with built-in MoS₂ lubricant — 25-year shelf life, superior elastic memory to self-compensate for droop-induced cross-section variation. Measure trunnion diameter at 4–8 circumferential locations per blade before ordering — each blade has its own droop signature. Stainless steel sleeves provide fresh running surface where existing bore is corroded or fretted.
IEC 60308:2024 · ISO 10816 · OEM reference: Voith, Andritz Hydro, GE Renewable Energy
Standards & Specifications
Governing Standards
| Standard | Body | Hydropower Sealing Relevance |
|---|---|---|
| IEC 60308:2024 | IEC TC4 | Governing system testing; OPS pressure acceptance criteria (fluctuation ≤ ±10%); hydraulic fluid quality requirements per contract |
| IEC 60193 | IEC TC4 | Model acceptance tests for hydraulic turbines; gate leakage limits; defines acceptable wicket gate bypass flow rates |
| ASME B31.1 | ASME | Power piping; governs penstock and spiral casing flanged connections, expansion joint design, and gasket specification |
| ASME B16.20 | ASME | Metallic gaskets for pipe flanges — spiral wound and ring-type joint; solid inner ring requirements by pressure class and NPS |
| ISO 4413 | ISO | Hydraulic fluid power systems safety; governs servomotor/OPS circuit design, seal specification, and fluid cleanliness requirements |
| ASTM D2000 | ASTM | Rubber material classification system; used to specify elastomer grade on engineering drawings for gate seals, gaskets, and hydraulic seals |
| DIN 7865 | DIN | Rubber profiles for hydraulic engineering structures; dimensions and tolerances for gate seal profiles (P, J, T, bulb types) |
| EM 1110-2-2104 | USACE | Hydraulic steel structures design; gate seal selection criteria, material specifications, and installation requirements for dam gates |
| ISO 3601 | ISO | O-ring groove design and dimensional tolerances; applies to cord-spliced large-diameter O-ring installations and standard O-ring connections |